Radio signaling system



Sept-.- 22, 1925. i 1,554,795

L. DE FOREST RADIO SIGNALING SYSTEM Filed May 10, 191 5 Patented Sept. 22,1925

UNITED STATES PATENT OFFICE.

LEEDE FOREST, OF NEW YORK, N. Y., ASSIGNOR TO DE FOREST RADIO TELEPHONE AND TELEGRAPH COMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

RADIO SIGNALING SYSTEM.

Ap lication filed May 10, 1915. Serial No. 27,025.

To'aZZ whom it may concern:

Be it know-n that I, LEE nE FOREST, a citizen of the United States, residing in New York, county of Bronx, State of New York, have made a certain new and useful invention in Radio Signaling Systems, of which the following is a specification.

This invention relates to radio signaling systems.

The object of the invention is to .provide a simple and efficient system for use in radio signaling.

provide a signaling system of the class referred to wherein the amplitude of the radiated wave trains is effectively controlled by a signaling device.

Further objects of the invention will appear more fully hereinafter.

The invention consists substantially in the combination and location of parts, and the various circuit arrangements associated therewith, all as will be more fully herein after set forth, as shown in the accompanying drawing, and finally pointed out 1n the appended claims.

Referring to the drawing,-

Fig. 1 is a diagrammatic view showing one form of circuit arrangement embodying my invention.

Fig. 2 is a similar view showmg a mod1- fied arrangement for accomplishing the purposes of my invention.

The same partis designated by the same reference numeral wherever throughout the several views.

In accordance with my invention provide a source of electrical energy lndlcated at 1. In the form shown, but to which I am not to be limited or restricted, 1 is a direct current generator, regulated by the adjustable resistance 2. Connected in the circuit of the current source, is a capacity, such as a condenser 5, and an inductance 6 in serles therewith, and choke coils 3, 3. 'A spark gap, illustrated at 4 is connected across the inductance 6 and capacity 5 forming therewith an oscillating circuit which may be utilized as a source of continuous oscillations. A radiating antenna 8 is connected to earth or ground 9 through inductance 7 which may be the secondary coil of an oscillation transformer the primary coil of which is the inductance 6 hereinbefore identified. Any other suitable form of coupling may be it occurs employed. An audion 10 including therein the well known forms of hot and cold electrodes such as the cold plate or wing electrode 11, the grid or intermediate cold elec trode 12, and the hot filament electrode 13, is associated with the antenna earth system through the spur 20 connecting the cold electrode'll to the antenna system. The filament electrode 13 is heated by a current source such as a battery 16, and controlled by the variable. resistance 17 in the usual p and well known manner. A microphone or A further object of the invention 1s to other suitable signaling device, as illustrated at 14, is connected between the grid electrode '12 and the filament electrode 13. If desired, and as shown, an auxiliary source of current such as a battery 15 may be included in this circuit, preferably with-itsnegative terminal connected to the grid electrodeso as to normally maintain anegative charge upon said electrode, but it is obvious that my invention is not to be limited in this respect.

Fig. 2 is similar to Fig. 1 exceptthat in this arrangement the microphone or signaling device is associated with the grid electrode by means of an additional circuit .con-

taining battery'21 and primary windin 19 p of a transformer,- the'secondary 18 of w ich is connected to the grid and filament electrodes 12, and ,13, respectively. It is obvious that any other form of coupling may be employed to couple the circuit of the microphone to the circuit ofgrid electrode 12.

In this arrangement an additional current source, such as a battery 22 is connected to the wing or plate circuit of the audion, to normally charge the wing or plate 11 positively' relative to the filament electrode 13. In both forms ofmy invention shown in the drawing, the plate or wing electrode 11 is in electrical'connection to one side of the filament electrode 13, and in the arrangement shown in Fig. 2, the current'source 22 is located in this circuit connection which includes the spur connection to the antenna. By means of the circuits here shown a shunt path from the antenna to the earth is provided through the gas of the audion and completely around the inductance 7 of the antenna earth system. The conductivity of this gas path is more or less afiected by the electric charge. momentarily residing in the grid electrode 12. The intensity of this charge is in turn affected by' the signaling device, such as the-microphone 14 which controls the potential impressed on the grid electrode 12 by the current source 15, either directly as indicated in Fig. 1, or inductively, or otherwise, as indicated in Fig. 2. In this way, a signal, such, for illustration, as a voice spoken into a microphone 14, will control the de cc of shunting resistance offered in the earth shunt circuit of the antenna system and thereby control the am plitudes of the radiated wave trains in accordance with the voice currents through the microphone.

The arrangements shown and described are somewhat similar, and perform similar functions to those shown in Figs. 12 and 14 of my Letters Patent No. 943,969, granted to me December 21, 1909, but my present invention illustrates a marked improvement thereover in the method of controlling radiation amplitudes by means of a signal, such as a voice.

While I have set forth the objects and nature of my invention and various arrangements for the accomplishment thereof, it will be understood that many other arrangements will occur to those skilled in the art, without departing from the broad scope of my invention as defined in the claims, and therefore, what I claim as new and useful and of my own invention and desire to secure by Letters Patent, is,

1. In a radio signaling system, a source of high frequency oscillatin current, a radiating antenna system associated therewith, an evacuated vessel containing hot and cold electrodes, a spur to the antenna connected to a cold electrode of said evacuated vessel, and an earth connection to the hot electrode of said vessel, means for impressing a positive charge of current upon said cold electrode and means for varying the conductivity of the space in said evacuated vessel between said hot and cold electrodes.

2. A system comprising an arc generator, a signal conductor in which said generator produces high frequency waves, a current supply line for said generator, a unidirectionally conducting electron discharge device operatively connected to and energized by current transferred through said line, and signal controlled means for varying the impedance of said discharge device.

3. A system comprising an arc, a unidirectionally conducting electron discharge device having a space current path, and a common source of current supply for said are and said path.

In testimony whereof I have hereunto set my hand on this 7th day of May A. D., 1915.

LEE nnFOREST. 

